Subsurface water quality model for western surface mine sites. Technical completion report

Regional similarities in chemical characteristics of shallow groundwater were indicated from hydrochemical data from proposed surface mining sites in North Dakota, Montana, Wyoming, and Alberta. Groundwater similarity characteristics were noted for dominant anions (sulfate and bicarbonate) and cations (sodium and calcium), pH (7-9), and electrical conductance of shallow groundwater (500 to 4500). A hydrogeochemical model was developed for this region, based on mineralogical data and unsaturated/saturated zone hydrochemical characteristics. Critical hydrogeochemical processes were considered. Mineralogical variability results in significant groundwater quality differences within/between proposed mining sites.